This invention pertains to the field of ground fault circuit interrupter devices, and in particular, to a ground fault interrupter device with miswire protection and indicator functions.
Ground fault circuit interrupters (GFCIs) are well known in the art. Their intent is and always has been to protect the electrical power user from electrocution when hazardous ground fault currents are present.
Historical problems with these devices include the possibility of line/load miswiring in the field by an installer or the eventual failure of the solenoid driving device, typically a silicon controlled rectifier, which causes the interrupter device to become inoperable while electrical power is still present, even under hazardous ground fault conditions. A variety of methods are used to prevent or attempt to prevent miswiring with varying levels of success. Preventing the problems associated with a defective solenoid driving device is inherently more difficult. Labels and installation instruction sheets have been used to prevent miswiring, but can be ignored by the installer. Solenoid burn-out has been revealed by testing the protective device with a test button, but the result of the test can be ignored by the user.
Briefly stated, an AC power line protection device such includes a resistive element connected at one end to a hot power conductor, and connected at another end to either a breaker coil operatively associated with a set of interrupting contacts or to a gate or base for a switch element. When AC power is miswired to the load terminals, the power interrupting contacts of the device trip due to the presence of the resistive element. The device does not work properly until AC power is connected to the line terminals, at which time the resistance element clears itself from the circuit. A testing switch permits testing the device after manufacturing without clearing the resistive element. An indicator lamp lights when the device is in the tripped condition and turns off when the device is reset. If the device is miswired after having been wired properly, i.e., the resistance element has cleared, the indicator lamp does not light when the device is tripped, and so provides a supplemental indication of miswiring.
According to an embodiment of the invention, a protection device connected between hot and neutral conductors of an AC power line includes a fault detection circuit including a breaker coil operatively associated with a set of contacts; at least one resistive element connected at one end to the hot conductor; wherein connecting AC power to load terminals of the protection device trips the contacts; and wherein connecting AC power to line terminals of the protection device permanently clears the at least one resistive element.
According to an embodiment of the invention, a protection device connected between hot and neutral conductors of an AC power line includes a fault detection circuit including a breaker coil operatively associated with a set of contacts; the set of contacts including hot conductor contacts and neutral conductor contacts; and an indicator lamp circuit including an indicator lamp wherein, when the protection device is properly wired to the AC power line, the indicator lamp lights when the interrupting contacts are opened by the protection device and the indicator lamp goes out when the protection device is reset and the interrupting contacts close.
According to an embodiment of the invention, a method of protecting against miswiring a protection device, wherein the protection device is connectable between AC power conductors includes the steps of providing a resistive element in the protection device such that the protection device trips out when miswired to the AC power conductors, and clearing the resistive element when the protection device is properly wired to the AC power conductors.
According to an embodiment of the invention, a method of protecting against miswiring a protection device, wherein the protection device is connectable to an AC power source includes the steps of providing an impedance in the protection device which prevents a set of contacts from closing if the protection device is improperly connected to an AC power source, and clearing the impedance when the protection device is properly wired to the AC power source.
According to an embodiment of the invention, a protection device connected between hot and neutral conductors of an AC power line includes first circuit means for preventing electrical contacts in the device from closing when the device is improperly connected to a source of AC power, and second circuit means for permitting the contacts to close when the device is properly connected to the source of AC power.
According to an embodiment of the invention, a protection device connected between hot and neutral conductors of an AC power line, wherein the device includes an interrupter having two contacts connected respectively to line hot and load hot terminals and two contacts connected respectively to line neutral and load neutral terminals, wherein the interrupter opens and closes to electrically disconnect and connect the load hot terminals, respectively, the device includes a resistor connected across the load hot and the line neutral terminals, and an indicator connected across the line hot and the load hot terminals, wherein the indicator indicates if a power source is connected across the line hot and line neutral terminals while the contacts are open.
According to an embodiment of the invention, a method for protecting against miswiring a protection device includes the steps of (a) preventing electrical contacts in the device from closing when the device is improperly connected to a source of AC power, and (b) permitting the contacts to close when the device is properly connected to the source of AC power.
According to an embodiment of the invention, a method for protecting against miswiring a protection device connected between hot and neutral conductors of an AC power line, wherein the device includes an interrupter having two contacts connected respectively to line hot and load hot terminals and two contacts connected respectively to line neutral and load neutral terminals, wherein the interrupter opens and closes to electrically disconnect and connect the load hot terminals, respectively, includes the steps of connecting a resistor across the load hot and the line neutral terminals, and connecting an indicator across the line hot and the load hot terminals, wherein the indicator indicates if a power source is connected across the line hot and line neutral terminals while the contacts are open.
According to an embodiment of the invention, a method for protecting against miswiring a protection device connected between hot and neutral conductors of an AC power line, wherein the device includes an interrupter having two contacts connected respectively to line hot and load hot terminals and two contacts connected respectively to line neutral and load neutral terminals, wherein the interrupter opens and closes to electrically disconnect and connect the load hot terminals, respectively, includes the steps of connecting a resistor across the load hot and the line neutral terminals, and connecting an indicator across the line neutral and load neutral terminals, wherein the indicator indicates if a power source is connected across the line hot and line neutral terminals while the contacts are open.
According to an embodiment of the invention, a protection device connected between hot and neutral conductors of an AC power line includes a protective circuit operatively associated with a set of interrupting contacts through a switch element; the set of interrupting contacts including a hot conductor contact and a neutral conductor contact; an indicator lamp circuit including an indicator lamp wherein, when the protection device is properly wired to the AC power line, the indicator lamp lights when the interrupting contacts are opened by the protection device and the indicator lamp goes out when the protection device is reset and the interrupting contacts close; the indicator lamp being in parallel with the hot conductor contact; and a resistor connected between the indicator lamp and the switch element, wherein the indicator lamp lights when the switch element is shorted.